Power slip assembly



June 7, 1960 2,939,683

W. H. SPIRI POWER SLIP ASSEMBLY Filed Dec. l0, 1956 3 Sheets-Sheet 1 June 7, 1960 w. H. sPlRx POWER SLIP ASSEMBLY 3 Sheets-Sheet 2 Filed Dec. 10, 1956 W21. y H Sp/Aw,

Ivre/vra@ June 7, 1960 Y iw. H. sPlRl f 2,939,683

POWER `SLIP ASSEMBLY' Filed Dec. 10, 1956 3 Sheets-Sheei'l 3 les [..qgmuu mail? 74 717/21. ylf.' l Sp1/QV,

nitd Statt-2S www() POWER SLIP ASSEMBLY Willy H. Spiri, Los Angeles, Calif., assigner to A'begg & Reinhold Co., Vernan, Calif., a corporation of Cahfornia Filed Dec. 10, 1956, Ser. No. 627,316

14 Claims. (Cl. Z55-23) This invention relates to improved power actuated slip assemblies for use in the rot-ary table of a well drilling rig. l

A conventional power slip assembly includes a number of slips for gripping and supporting a well string, together with means forfpower actuating the slips vertically between active lowered positions and elevated inactive positions. Ordinarily, the slips are mounted to a stationary support vstructure which projects upwardly at a side`V of the rotary table andwhich includes a suitable power Apiston or other `power unit. for raising and loweringthe slips. One diiiiculty encountered, however, has been that of` accurately centering the slips when thus supported, and of always maintainingthe proper centering of the slips under actual conditions of use.

A major object tot the Vpresent invention is to provide an improved power slip assembly in which the slips are centered much more accurately and effectively than has been possible in prior arrangements. To achieve this purpose, the slip support structure is mounted to turn with the rotating portion of the rotary table, rather than being attached to the outer stationary portion of the table, to thus always maintain proper centering 'of the slips with respect to the rotating parts. Preferably, the

slip support structure is mounted to the master bushing` are mounted and which is vertically actuable relative gto'- the support section to move the slips between active-landinactive positions. f

Desirably, the power unit for actuatingthe carrier section' andgslips is alsorotatable .with the table and'the other sections `of the device, :typically being'` one or 'more power cylinders and pistons interposed vertically between Fig. 6 is a diagrammatic representation of the fluid system of the apparatus; and

Fig. 7 is a `fragmentary vertical section showing a slightly variational form of the invention.

IReferring first to Figs. 1 and 3, I have shown at 10 a conventional well-drilling rotary table structure including the usual outer stationary section 11, and an inner relatively rotatable power-driven section `12. Within the rotating portion 12 of the rotary table, there is mounted a master bushing 13, containing a pair of slip bowl segments 14 within which a number of slip elements 15 are received. These slip elements 15 are movably carried by a supporting ring 16, which is in turn removably carried byA a ring 17. Ring17 is vertically actuable relative to a body 18, by means of a pair of iluidactuated piston and cylinder mechanisms A19 to'which compressed air or other actuating'uid is fed through a feed ring structure 20. The body 18 is mounted to masterbushing 13 for rotation therewith, so that all of the parts carried by body 18, including n'ngs 16 and 17 and slips 15, may turn with the master bushing and the rotary table.

The outer stationary portion 11 of the rotary table 10 is mounted vin any suitable manner to a supporting frame structure. This outer section 11 includes an annular portion 21 within' which the smaller diameter annu*l lar rotating section 12 of the table is mounted for relative rotation about theverti'cal axis 22 of the apparatus.`

l structure, .typically including two annular seriesof roller bearings represented at 23 in Fig. 1'.' The sectiony 12 of the rotary table is Vpower-driven'rotatably about kaxis `22 by any suitable drive mechanism (not shown).",Th inner rotating sectionfmay carry lan annular outwardly and then downwardly extending element 24, suitably attached to section 12, as by screws 25. The outer section 11 may include a bracket member 27 at one side, welded toy element 12 and projecting rst outwardly therefrom,V

and then upwardly at 26.

Y and having a lowercylindrical portion, and an upper non-circular and preferably Isquare portion 30. This upper portion 30 is of a size to projectV laterally beyond the diameter of lower cylindrical portion 29 of opening the two sections. Actuating. pressure fluid,.su'ch as.com`` pressed air, maybe fed to thevpower units through a pair of communicating feed rings, one of which 'turns with the table and 4the other of which is non-rotating.

The above and other features and objects ofithe present invention will be better understood from the follow-V ing detailed 'description ofthe typical embodimentillu'sy trated inthe accompanying"VV drawings in which: v

Fig. 1 is a vertical axial section through a well drilling rotary table and power slip assembly constructed in accordance with the invention, the view being taken 50. figuration and is preferably formed of a single piece of krigid metal extending continuouslyl entirely `about the 28,' to provide an upwardly facing shoulder on `which the master bushing 13 is supported. v v

:The master bushingv 13 is generally annular in concircularextent of bushing 13. Externally, bushing 13 has a lower cylindrical portion 32 and an upper noncircularand preferably square portion 33, with these surfaces 32 and 33 and an intermediate-shoulder-34 being shaped the same as surfaces 29, 30 and 31, respectively,

of .section 12 of the rotary table, to engage those surfaces in a manner positively supporting the bushing i13 in the rotary table, and effectively driving the bushingv with the rotary table about axis 22.

The ring 18 is a flat horizontally lextending annularv rigid plate centeredabout axis 22 and located above bushing 13. This ring is lrotatably keyed to and driven by bushing l13 by means of several (preferably four) ciri cularly spaced cylindricalpin's 140, which project downwardly from ring 18 into a number of cylindrical sleeves 141 contained within recesses 142 in bushing 13.` The' pins are rigidly welded or other-wise attached to ring,

18, as arengfour sleeves143 which are disposed about upper positions of the pins. The'rlower sleeves 141 are rigidly welded or otherwise securedto bushing 13, The

Patented Junev 7, 1960 pressure aasaees engagement of the lower ends of sleeves 143 with the upper surfaces of bushing 13 and sleeves 141 positively supports the ring 18 in the Fig. l position relative tothe rotary table and bushing, while at the same time rotatively keying ring 1S to the` bushing. for rotation therewith. As will be apparent, ring 1S 'and the. carried parts. may` all be. detached from the. rotary table by merely lifting ring 18 upwardly so that pins 144)Y will be withdrawn from recesses 142 and their linerV sleeves 141. Thefour recesses 142 may be located within the four corners of. the upper. square portion 33, of bushing 13. i

Internally, the master. bushing 13 has a lower inwardly.

facing cylindrical surface 35. and an. upper inwardly facing cylindrical surface 36 of somewhat increased diameter. The sliprbowl structure received within bushing13; may in some instances consist of a single ainnular body, but preferablyl is formed. `of two semi-circular and complementary segments 14, having outerV reduced diameter cylindrical surfaces 37 engagingsurface 35 of bushing 13, and; having upper increased diameter cylindrical surfacesv 3S, engaging surface 3,6L of bushing 13. Between these surfaces 37 and 38, the, bushing 13.and the slip bowl segments 1 4 have, annular shoulders 39 which are inter-engageable to.V positively support the slip bowl segments Within bushing 13- 4 The inner surfaces of slip bowl segments 14 have upper portions 4(4)- wliiicl'ly taper prDgreSively downwardly to a reduced diameter at 4,1, thetaper of these surfacesbeing.

preferably.frustro-conical1 as will be apparent from Fig. lL T -hese surfaces 4d; engage the outer correspondingly.taperE ing. surfacesy 4 2 of a series of circularly spaced slips 15, solthat downward movement of the slips 15. relative to slip bowlsegments 14,-and the rotary table causes the. slips tobeA displaced radially inwardly against a drill pipeV or other pipe. vextending vertically through the apparatus along axis 22. Beneathl the downdwardly tapering surfv faces 40 of segments 1 4, these Segments may4 have inner.

clylindrical surfaces 43.

Each of the` slips 15 has an inner gripping surface. 44 which is irregularipzred in some manner to effectively grip end support awell pipeV engaged by the slips. To form this surface,v each` slip 15 may Vcarry a vertical series of.

grippingfelementsflfta, whose inner edges function as the irregularities for gripping the pipe.A The gripping. edges of the variousvslip surfaces 44 ofV each of the. slips. lie essentially in a common vertical plane, to allrsimultaneously engage the pipe, and these edges `may curve slightly.. about axisV 22, if desired, toconform somewhat to. the.. curvature of the outer surface of.; the pipe. The various.

slips 15 `a're'of rathersmall extent circularly about axis 22 (see Fig. 2) sothat a. large number of the slips may. be.

provided to engage the pipe atp a` number of differentV locations about its circular extent.` Preferably, I` utilize asmany of the slips l as can practically be groupedf around the size of pipe for which the device is designed.`

Asy previously mentioned, all of the slips lfare supportedby a common annular ringl 16. ring 16 is spaced above the slips, and contains an inner opening 45 centered about axis 22 for passing the well pipe vertically through ringk 16. The slips are individually suspended from ring 16 by means ofva number of'linksvi, each.of.

which is'pivotally. attached at 47 to ring 16, and is pivotally attached at a lower end 48 to the associated slip. 15. These links 46 allow slips 15 to move radially toward and away from axis 22, in correspondence with theverticalmovement of the slipsV relative to the wedge surfaces 40 of segments 14. The pivotal connections at 47 and 48 are of course such asto maintain links 46 and slips.15 inv a. desired orientation relative to ring 16 Vsov that the inner gripping surfaces 4.4 ofthe slips alwaysface directly inwardlytowards axis 2N2,Y

Theproper,positioning.of each slip relative tothefother slips in allV conditions Yof the apparatus is* further conf trolled by the provision, of a series of links 49 whichrnovably interrogati?? adasetslra @transgene-.fs there,

within which there is mounted a vertical shaft ork pin 51, fixed relative to the slip, and extending through openings 52 in a pair of the links 49. These two links 49 connected to one of the slips 15 extend ingenerally opposite circular directions from that slip, for attachment at their ends to a pair of similar links connected to adjacent slips. The connection between these links is effected by means of vertical pins*V or' shafts 53 (see Fig. 2), which extend through openingsv in the endsV of the links. Thurs, eachy pair. of adjacent slips 15 are connected together` by a pair of the links 49, which are pivoted respectively to they two slips, and are also pivotally connected at their opposite ends to each other. This type of linkage freely allows movement of the slips radially toward and away from axis 2.2, but tends to retain all of the slips at essentially the same distance from the axis in a particular setting of the apparatus, and ,also very effectively holds all of the slips in properly oriented positions in which their inner irregu larized surfaces 44 extend vertically as seenA in Fig. l for proper engagement with the well pipe 54. This is true in. partbecause the pivotal connections at 51--52 connect each of thelinks 49 to an associated slip 15 for pivotal movement yabout anaxis 55 which is fixedl relative to that` slip, and because the connectionsv formed at 53 between thelinks L@connect the linksfor pivotal movement. about axes. which in all. conditions extend parallel to axes 55.

The ring17 which carries slip-supporting ring 16` isk disposed about the latter, and :if desired may be` formedofV several rigidly.. interconnected parts, as shown. More specical'ly, thisv ring 17 may include Ian. upper annular element 56 'and a lower annular element 57 retained vertically spaced relation byanouter short cylindricalA ring 58 suitablywelded to both of the elementsl 56 and 57.. The inner ring 16 may be removably supported from. outen ring 17 by means of a pair of diametr-ically-l opposedV fiat slide elements 59, which are confinedV between plates 56 and 57 for sliding movement radially. toward andwaway from axis 22. These elements 59 have inner arcuatelyrcurved edge portions 60 whichy are receivable Withinfan outerA annular radially outwardly facing` groovel formed-in the outer surface of ning-16', so that therengagement of elements S9 with ring 16. ailongarcuatev are-as 62 at the upper sideof the edge portions 60 ofl` elements159gacts to very effectively support ring 16 and thevcarried slips from ring 17. As will be apparent, the curvature of theinner arcuate` edge portions 60ct elements 59; is the same as. the curvature of the annular'- groove.. 61.v formed in element` 16. The elements 59v-areactuable radially toward and away from axis-22am into and: outgof groove 61 by means of a pair of pins 63 which.arerigidlyv lattached to. elements 59 vand project downwardlytherefrotn through la pair of slots 64 formedinythenlower plate S7 of,` element 17. Slots 64 are of a length to allowr just sufficient sliding-- movement ofelements. 59 torfrnove theseelements. betweentheir active.

positions. .of'reception. withiny Ygroove 61, and `radially,

outwardlywdisplaced,retracted .positions which elements Y SStgarenot` received withngroovel, tothusaillow upward removal of elementsv 16 and the carriedv slips from the rest ofrtheapparatus.` The'parts 59,may bevreleasablyheld in their inner positions by means of a pairloflbalf plate 57 of ring 17 As will be apparent, the ballV detente 65. are'urgedfupwardly with suicient-.force toeffectively hold parts 59. intheir. inner. `active-positions, and yetfthe force of springs 67 'is sufciently light to be overcornevby manual retracting forceexerted against.. actuating pins;63.

The upper rings 16 land 17 andthe.carriedslips151..are-

adapted ,to b e power-actuated vertically. betweenithe lower full li-ne position of Fig. 3, and the upper broken line-.

, position ofthat gure.V :Inthe upper position of Fig.,3, the slips are raised sufficiently high to be free ofengagement with wedge surfaces 40 of slip bowl segments 14, so that the slips 15 are lable to hang freely directly downwardly from ring 16, and Vthus are displaced farther away from the axis 22 than'lin the Fig. 1 position. Thus, when the slips 15 are in this way retracted radially outwardly, the opening through the entire apparatus is sufficiently enlarged to pass an enlarged tool joint or other increased diameter element vertically through the apparatus. As the rings 16 and 17 and slips are subsequently lowered toward their Fig. 1 position, the wedge surfaces 40 and 42 codact to progressively cam slips 15 toward 22 and into tight gripping engagement with` a pipe 54 received the apparatus;

The vertical actuation of ring 17l relative to the lower mounting ring 18 is effectedV by means of the two previously mentioned fluid pressure operated piston and cylinder mehanisms 19. During such vertical actuation, the upper ring 17 is held against lany tilting movement or lateral displacement; that is, is held ina proper orientation with respect to axis 22 andnriug v18,by means of two sets of levers at opposite sides of the central opening, each set of levers including a frst'lever 70 and a second lever 71. The functioning of these levers will be discussed in greater detailY at a laterpoint. Each piston and cylinder mechanism 19 includes a cylinder 72, one of whose ends has a lug portion 73 which is pivotally attached iat 74 to a bearing lug 75 rigidly secured to the upper surface of ring 18.v The piston of each mechanism 19 has its piston rod 76 projecting from the opposite end of'cylinder 72 and pivotally connected at 77 to a bearing lug 78which is rigidly attached to the Vunderside ofring 1`7." The pivotalfconnection at 74 (see Fig. l) allows upward swinging lmovementof the left end' of cylinder`72 about 'a horizontal axis, while the pivotal connection at 77 permits relative pivotal movement of rod 76 andlug 78 about 'a second horizontal axis extending parallel to the axis at 74. Each of the cylinders 72 extends at an inclination to the horizontal in the lowermost position of Fig.` l, so that when pressure ii'uid (for example, compressed air) is fed to the lower end of cylinder 72 through inlet 79, the piston and its rod 76 exert force against lug 78 having an upward component, thus resulting in upward displacement of ring 17 relative to ring 18. As seen clearly in Figs. 2 and 3, the two piston and cylinder mecha-nisms 19 are located at opposite sides ofthe 'central pipe passing opening, the lugsr 75 and 78 being rigidlyyattached to rings 18 `and 17 respectively toward their outer edges by mea-ns of suitable screws represented at 80 (Fig. 2).

' The structure 20 for feeding pressure fluid to cylinder 72 includes two complementaryrigid metal rings 81 and 824 (see Figs. l and 4), which are suitably secured together in any suitable manner as vby screws 83, and which are rigidly attached to the underside of ring 18, as by welding of the upper element 81 to ring 18. The two opposed faces of rings 81 and 82 are recessed, to receive therebetween al third rigid preferably metal ring 84, with seal rings 85, 86, 87, S8, 89 and 90 being received between ring 84 and the other two rings. `As will be ap parent, all of the various rings 81 through 90 are annular and are centered about the vertical `axis 22 of the lapparatus, and have the cross sectional configurations represented in Fig. 4. Compressed air or other pressure fluid may be fed to a pair of radial passages 91 and 92 in ring 84 through a pair of radially extending pipes 93 and 94 threadedly connected into the outer ends of passages 91 and 92. These-pipes 93 and 94 are received Within and passroutwlardly through aV pair of notches 95 cut -i-n the upper edge Aof stationary element 27, which notches are of a-fwidth'V corresponding substantially to Vthe diameter of pipes 93 and 94 to retain these pipes and the connected ring84 againstrotation with vrings 81 and 82. The notches 95 y#are open *at* their upper sides to |allow pipes 93 and 94 to movel upwardly out of the notches whenever the slip mechanism is removed Ifrom the rotary table.

Pipes 93 and 94 are of course rigid, but may be connected at their outer ends to exible hoses 93a and 94a, to allow for the discussed upward removal of the apparatus from the table. Y

Passage 91Y in ring 84 connects through apassage 96 with a space 97 at the underside of ring 84, which space in turn communicates' lwith the previously mentioned line 79'connecting into the Alower end of the two cylinders 72. Similarly, the second passage 92 communicates through a passage 98 with an upper space 99, which is connected to a line 100 leading to the upper ends of the two cylinders 72. The seal rings through 90 may be formed of a resilientlydeformable seal material, such as rubber or felt, and have the illustrated configurations to effectively confine the air or other pressure fluid against leakage from the two annular spaces 97 and 99, so that uid is effectively fed from the stationary lines 93 and 94 to the rotating lines 79 and 100 through the ring vtype swivel connection of Fig. 4. Referring now to Fig. 6, if the pressure uid utilized for actuating mechanisms'19 is compressed air, that air may be fed to the apparatus froma suitable supply tank 101, which is continuously maintained under the desired pressure by a pump or compressor 102. From tank 101, the compressed air mayow to a multiple position valve 103, which functions asa reversing valve for selectively admitting pressure uid Yto-eithe'r line'93 or line 94, with the second of the lines being a return line through which pressure fluid ows back to valve 103 for discharge through an outlet represented at 104. Thus, valve 103 may be set in a condition for admitting compressed Vair or other pressure fluid to line 93, :to pass through the swivel assembly of Fig. 4 into line 79 leading to the lower ends of cylinders 72, to thus cause the cylinders to elevate rings V16-and 17 and the carried slips 15. In this'condi-l tion, the pressure uid 'from the upper lends of the cylinders returns through lines and 94to` the valve, for discharge at104. In the reversed condition of valve 103,

pressure uid is admitted to the upper ends of cylindersV charged lfrom the valve through outlet 104 may be con? ducted through a suitable line back to the inlet side of pump n102, for recharging into pressure tank 101.

The two levers 70 are pivotally connected at rst ends 105 to ring 17, while the levers 71 are pivotally connected at their corresponding ends 106 to the upperside of ring 18. To effect Ithe pivotal attachment of levers 70 to ring 17, these levers are rigidly attached to opposite ends of a horizontally extending connecting shaft 107 (see Fig. 2). More-specifically, each end of this shaft may carry a nut 1,08, which tightens a washer 109 against the end of a corresponding lever 70, the latter containing an opening 110 through which a reduced portion 111 of shaft 107 passes. When nut 108 is tightened, it holds lever 70 against -a shoulder 113 formed on shaft 107, to thus secure the -two levers 70 in iixed'relation to shaft 107. The shaft passes through a pair of bearing lugs 112 attached to the underside of ring 17 in fixed relation thereto, to thus mount shaft 107 and the attached levers 70 to ring 17 for relative pivotal movement about the horizontal axis of shaft 107. The bearing lugs to shaft 107 in a relation such that these levers will always project in the same direction from shaft 107, radially o the axis of that shaft.

The left ends of the two levers 71 (as seen in Fig. l) are rigidly connected to a horizontal shaft 115, in the same way that levers 70 are connected to shaft 107, and

the unit formed by levers 71 and shaft 115 is pivotally attached to the upperside of ring 18 for swinging movement about the horizontal axis of shaft 115 by means of a pair of spaced lugs 116 functioning the same as lugs 112 of the upper shaft. The axes of shafts 107 and 115 are directly parallel :to each other and liey in a common vertical plane.

At their right ends (Figs. 1 and 2) levers 70 and 71 each carry a transverse stub shaft 117, secured to the respective levers by nuts 118, and rotatably carrying individual rollers 119, which are rotatable about axes extending parallel to the axes of shafts 107 and 115. The rollers 119 which are carried by shafts 70 `aremovably received within a pair oi guide channels 120 rigidly attached to the upperside of ring 118,Y while the rollers 119 carried by levers '771 are correspondingly movably received within a pair of guide channels 121 rigidly attached to the underside of rings 17. Each of'these guide channels guides the associated roller 11'9 for movement only horizontally relative to the associated ring 17 or 18, and in a direction directlsl radially of the shaft 107 .or 115 which is attached to the opposite side of the same ring. For confining the roller, each channel forms a horizontal passageway dimensioned to exactly receive the roller, and having shoulders 122 (Fig. 3) extending along its open side for conning the roller against displacement laterally out of the passageway. Intermediate their ends, the levers '70 and 71 curve arcuately away from axis 22 (at 123), to avoid interference with the inner slip mechanism. At their exact midpoints, the levers 70 and 71 of each set of levers are pivotally interconnected for relative pivotal movement about an axis 124, which axis is exactly midway between the axis of shaft 107 and the axis of the roller 119 carried by lever 70, and is also exactly midway betweenv the axis of shaft 115 and the axis of the roller 119 carried by lever 71. Also, axis 124 is of course parallel to the axes of shafts 107 and 115 and rollers 119. The attachment together of levers 70 and 71 at axis 124 may be effected by means of a pair of headed pivot pins 144, which are threadedly connected into levers 70 and pass through bushing sleeves 145 contained within openings 146 in levers 71. Y

As will be understood, the connection formed between the two rings 17 and 18 by levers 70 and 71 allows vertical movement of ring 17 relative to ring 18, but very positively holds ring 17 in a proper horizontal position and in proper ver-tical alignment with ring 18 in all positions of the upper ring 17. The upward movement of ring 17 may be limited by engagement of rollers 119 with four stop screws 125 which are adjustably mounted to endwalls 126 of channels |120 and 121.

To assist in supporting the weight of drill pipe 54 when engaged by slips '15, I prefer to provide a pair of spring units 127, positioned at opposite sides of axis 22, and eachv including a vertically extending coil spring 128 (see Fig. 3) of very substantial strength. This coil spring is contained within a pair of vertically telescopically movable tubular sections 129 and 130, the former of which bears upwardly against upper ring 117, and the latter of which is rigidly attached by screws 131 to lower ring 18. In thelower position of Fig. 3, the downward movement of ring 17 is limited by engagement of that ring with the upper end of tubular member 130. In all positions of ring Y17, the two springs 12S remain under considerable compression,to.a1ways exert a very substantial upward force against 'ring 17 tending to support the weight of pipe. 54.

In-describing the operation ofthe.illustratedjapparatus,

assume Yfirst that the apparatus is assembled to the Fig. l condition, but with the upper ring 17 in its broken line elevated position of Fig. 3. If it is then desired to actuate the slips 15 to positions in which they will eifectivelyV supportthe well spring 54 from the rotary table, the operator actuates the valve y103 of Fig. 6 to a position in which it admits compressed air or other pressure tluid through line 94, swivel unit 20, and line to the upper ends of cylinders 72, to thus cause the pistons to move downwardly within the cylinder 72, and thus lower the ring 17 and the suspended Slips 15 to the full line position of Fig. 3 (the Fig. 1 position). As the slips move downwardly, they are cammed radially inwardly by surface 40, to move into tight holding engagement with the well pipe 54. Thus, the well pipe is effectively supported by the slips in xed relation to the rotatable section 12 of the rotary table. When it is desired to release the pipe 54, the valve 103 may be actuated to a position in which pressure iiuid is admitted to the lower ends 79 of cylinders 72, and is discharged from the upper ends of the cylinders, to cause piston rods 76 to exert upward forces against ring 17, to thereby retract the ring upwardly to its broken line position of Fig. 3. In this position, the slips are able to swing outwardly away from the well pipe 54, and thereby free the pipe for vertical movement within the well. In the lower full line position of Fig. 3, ring 17 may be horizontally aligned with the floor structure 132 of the drilling rig.

y Duringthe radial movement of the slips l15 into and out of engagement with the pipe 54, the links 46 and 49 act to hold Vthe various slips in a proper interrelationship assuring that all .of the slips will engage and hold the pipe. Specifically, the links 46 keep the slips 15 always in positions in which their inner surfaces 44 face inwardly toward axis 22, and the links 49 secure the adjacent slips together for movement in union, and also maintain the inner surfaces 44 of the slips always in essentially vertically extending positions (as in Fig. l).

If it is desired, the entire slip unit can be removed from the interior ofl the apparatus, by merely retraoting yends 63 and their attached parts 59 radially outwardly, to move parts 59 out of groove 61, so that lring 16 and the suspended slips 15 can be withdrawn upwardly from the rest of the apparatus. When the slips are in use, they are at all times very effectively heldin properly centered position relative to axis' 22 by virtue of the direct conneotion of the main supporting body 18 to master bushing 13; 'that is, the slip structure is all attached directly to the rotating portion of the rotary table, rather than to the outer stationary portion 111 of that table as haspgenerally been the case in prior power slip arrangements. When i-t is desired to remove the entire power slip apparatus, this may be done by lifting the ring 18 and'all of the carried parts upwardly away from the rotary table, withdrawing pins from thesleeves 141 within which they are contained, to leave the bushing 13 accessible for reception of a kelly-drive bushing or other unit. When a kelly-drive bushing is employed, it may have pins corresponding to those shown at 140 and received within the sleeves` 141 to rotatably drive the kelly with the bushing.

Fig. 7 represents fragmentarily a slightly variational form of the invention which is adapted for handling a dling a smaller pipe, the two semi-circular slip bowl seg ments `14 are made thicker than the segments 14 of they tirst form of the invention, with the result that theslips 15 are cammed inwardly farther than ill Figs.. 1-6, as

permitted -by links 46', to thus engage and support the smaller size pipe.

vlclairn: E'

l. YApower, slipassembly for use with a well agences rotary table having a stationary portion and Aztrbtating vertically relative to said support betweenilower active positions and upper inactive positions, a carrier structure movably mounted to said support structure and carryingA and movable vertically with said slips, means for actuat-v ing said carrier structure and slips vertically relative to said support structure, and a plurality of levers pivotally connected `near their ends to said support structure and toY said carrier structure respectively and pivotally connected to one another at locations intermediate their ends and positively maintaining the carrier structure'against tilting movement from a predetermined aligned position with respect to the horizontal as the carrier structure moves vertically to diierent positions.

2. A power slip assembly for use with awell drilling rotary table having a stationary portion and a rotating portion turning about a vertical axis, said assembly comprising a support structure, means for mounting.: said support structure to said rotating l portion of` the. rotary table and for rotation therewithabout said.faxis, slips movable vertically relative vto said support b'ef tween 4Vlower active positions and upper inactive Vp0'- sitions, a carrier structure movably mounted to said support structure and carrying and movable vertically with said slips, means for actuating said carrier structure and slips vertically relative to said support structure, and aligning means for positively maintaining said carrier structure in a predetermined position of alignment with the horizontal as the carrier structure moves vertically to diierent positions, said aligning means comprising first and second levers having first ends pivotally connected to said support structure and said carrier structure respectively and having second ends connected to said carrier structure and support structure respectively for relative pivotal and horizontal movement but restrained against relative vertical movement, and means pivotally connecting said levers together intermediate said ends thereof.

3. A power slip assembly as recited in claim 2, including two of said pairs of levers between said support structure and said carrier structure at opposite sides of said-axis, said actuating means including two inclined pistons and cylinder mechanisms at opposite sides of said axis and connected at opposite ends to said support and carrier structure respectively to actuate the latter vertically relative to said support structure.

4. A power slip assembly as recited in claim 3, including a first rotating fluid feed ring turning with said support structure and a nonrotating feed ring for supplying fluid to said iirst ring.

5. A power slip assembly for use with a well drilling rotary table having a stationary portion and a rotating portionY turning about a vertical axis, said assembly comprising a support structure, means for mounting said support structure to said rotating portion of the rotary table and for rotation therewith about said axis, slips movable vertically relative to said support between lower al movementrelative to the-support.A structure'andf'tsv` straining the carriervstructure against relativey tilting or horizontal shifting movementV upon actuation'of said in? clined vpiston Vand rcylinder mechanism and in spite of the inclination thereof.

6. A power slip assembly'for use with a well drilling rotary table comprising a support structure, a carrier' structure mounted to said support structure for relative vertical movement,a plurality of circularly spaced slips movably suspended from said carrier structure, a plurality of links suspending said slips respectively and each pivoted at an upper end to said carrier structure and at a lower end to one of the slips to allow radially inward and outward movementr of the slips, and a plurality of pairs of additional links movably connecting adjacent slips together, each of said pairs of additional links including akirst link pivotally connected, toward a tirst end thereof,"to a iirst slip for relativev pivotal movement Iabout `airst generally verticalraxis, a second ment abouta second generally vertical axis, and means pivotally AconnectingY said first and second links together toward secondV ends thereof 'for Vpivotal movement relative to one -another about athirdygenerally,verticalv axis'.l

`7. A powei slip assembly vfor use with a well drilling rotary table having a stationary portion and a rotating portion turning about a vertical axis, said assembly comprising a support structure, means for mounting said support structure to said rotating portion of the rotary table and for rotation therewith about said axis, slips movable vertically relative to said support between lower active positions and upper inactive positions, a carrier structure mounted to said support structure for rotation therewith and for vertical movement relative thereto, an essentially annular member centered essentially about said axis, connector means detachably connecting said essentially annular member to said carrier structure for vertical movement therewith, means movably suspending said slips from said member, and means for actuating said carrier structure, and thereby said member and slips, vertically relative to the support snucture, said essentially annular member and slips being completely detachable from the carrier structure, said carrier structure being essentially a ring'disposed essentially about said member, said connector means comprising a pair of lock elements movably mounted to said ring and each 1 receivable within an outwardly facing recess in said which said rst mentioned means include pins project-V ing downwardly from said support structure and receivable withinidriving recesses in a master bushing contained in said rotating portion ofthe rotary table.

l0. A power slip assembly as recited to claim 2, in Y which said first mentioned means include externally nonactive positionsV and upper inactive positions, a carrier structure movably mounted to said support structure and carrying and movable vertically with said slips, a piston and cylinder mechanism turning with said support structure and said carrier structure and operable to actuate the carrier structure and slips vertically relative to said support structure, said piston .and cylinder mechanism having an upper end pivotally connected to said carrier structure and a lower end pivotally connected to said support structure and being positioned to swing upwardly from a retracted inclined position to a more vertically extending position as the carrier structure is elevated relative to the support structure, and positioning means guiding said carrier structure for only verti- Ving adapted to be mounted in said rotating portion of the table, and means for attaching said support structure to said bushing for rotation therewith.

l2. A power slip assembly as recited in claim 2, in which said actuating means comprise a iiuid pressure operated piston and cylinder mechanism for raising and lowering said carrier structure.

asados?,

carrier structure, a irst fluid inlet ring turning with saidV support structure, and a second nonrotatingv uid inletv ring for feeding uid to saidv first ring, and sealed, with respect thereto, both of said rings being centered. about.

said axis and spaced outwardly therefrom.

L4. A power slip assembly for use with awellldrilling rotary. table having a stationary portion and a rotating portion turningy abo'rut a vertical. axis, said assembly comprising a support structure, meansfor mountingsaid support structure to said rotating, portionlof the rotaryy tableV and for rotation therewith about said axis, slips.

movable vertically relative to said support between lower active. positions and. upper inactive positions,. a carrier structure movably mounted to said support structure and. carrying and movablev vertically with said. slips,v a

piston and cylinder mechanism turning. with said support structure and said carrier structure and operable.

to. actuate the carrier structure and slips. vertically relative to saidv support structure, saidr piston and cylinder mechanism having an upper end pivotally connectedto said carrier structure and a lower end pivotally connected to said support structureand being positioned to swingI upwardly from a retracted inclined position to a more vertically extending position as the carrier struc-4 ture isA elevated relative to the support structure, and positioning means guiding said carrierl structure for only verticalmovement relative to the support structure and restraining the carrier structure against relative tiltingy or. horizontal shifting movement upon actuation of said inclined piston and cylinder mechanism and in spite of the inclination thereof, said positioning means including a plurality of levers pivotally connected near their ends' to said support structure and said carrier structure respectively and pivotally connected to one another at locations intermediate their ends and maintaining thel carrier structure in predetermined orientation with respect to said support structure during said relative vertical movement.

References Cited in the file of this patent UNlTED STATES PATENTS 

